This invention relates to a composite motor/generator driving two rotors with a single stator.
Tokkai Hei 11-275826 published by the Japanese Patent Office in 1999 discloses a motor/generator which drives a plurality of rotors by applying a composite polyphase current to a set of stator coils. The invention of Tokkai Hei 11-275826 was filed to United States Patent Office as patent application Ser. No. 09/275,785 filed on Mar. 25, 1999 before the priority date of this invention and was granted as U.S. Pat. No. 6,049,152 after the priority date of this invention.
In this motor/generator, the composite polyphase alternating current comprising phases with a fixed phase difference is supplied from an inverter to coils of each phase in the stator. This prior art discloses a motor/generator with a ratio of magnetic poles for the two rotors of 1:, 2:1 or 3:1.
When the ratio of magnetic poles in the magnets of the two rotors is 1:1, it is possible to rotate a first rotor directly with the rotation of a second rotor by utilizing a magnetic coupling effect without applying a current to the stator coils.
Conversely this also means that when the second rotor is rotated, the first rotor may undergo unintended rotation.
A hybrid vehicle couples the drive force of an engine and a motor to charge a battery and drive the vehicle.
In the hybrid vehicle using the above type of motor/generator, when one of the rotors is rotated by the engine for charging the battery in a state when the vehicle is not moving, the other rotor and a propeller shaft of the vehicle coupled therewith may also be rotated. This operation may therefore result in an unintentional movement of the vehicle. When on the other hand, the rotor connected to the propeller shaft is driven for the vehicle start, the other motor connected to the engine is also rotated irrespective of the state of charge of the battery. This operation may result in an unnecessary engine operation.
Further, when the two rotors of which the ratio of magnetic poles of the magnets is 1:1 are driven as motors by supplying a composite polyphase current to the stator coils, it is difficult to control the rotation of the two rotors independently.
It is therefore an object of this invention to generate magnetic coupling while preventing unintended rotation of the rotor.
It is a further object of this invention to enable independent rotation control two rotors of which the ratio of magnetic poles of the magnets is 1:1 by supplying a composite polyphase alternating current to a single set of stator coils.
In order to achieve the above objects, this invention provides a motor/generator comprising a first rotor provided with a plurality of magnetic poles by a magnet, a second rotor provided with a plurality of magnetic poles by a magnet and a plurality of rotor coils, and a stator provided with a plurality of stator coils applying a rotational force on the first rotor and the second rotor when a composite polyphase alternating current is supplied to the stator coils.
This invention also provides a motor/generator comprising a first rotor provided with a plurality of magnetic poles by a magnet, a second rotor provided the same number of magnetic poles as the first rotor by a magnet, a stator provided with a plurality of stator coils applying a rotational force on the first rotor and the second rotor when a composite polyphase alternating current is supplied to the stator coils, and a device which limits the rotation of the second rotor in a specified direction.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.